It still remains unclear whether muscular activity on the treadmill(T) differs compared to overground (O) running. The purpose of this study was therefore to examine possible differences in muscular activation between T and O. 14 healthy runners were analyzed in a neutral running shoe at 12 km·h
$^{-1}$
on a treadmill and in a field test. Muscular activity (EMG) of the tibialis anterior, peroneus longus, and soleus were measured. Time and amplitude quantities were assessed during the gait cycle. The EMG of the peroneus longus exhibited a later onset, a later maximum and shorter total time of activation (p<0.05) in O. The soleus showed a higher amplitudes in O during the push-off phase(p<0.05). Altered peroneus longus activity may indicate its role as an ankle stabilizer and demonstrates a compensatory response due to changing mechanical conditions. Weaker amplitudes of the soleus in the push-off during T suggest adaptation to the movement of the treadmill belt, and/or changes in load receptor input. Differences in muscle activity between T and O running must thus be taken into consideration in studies of neuromuscular control of movement.
